1. Field of the Invention
The present invention relates to a printer apparatus.
2. Discussion of the Background
A printer apparatus is an apparatus in which, while a printer head formed with a number of nozzles is relatively moved with respect to a printing medium, ink droplets are ejected from a nozzle of the printer head to a printing medium to draw information such as a character, a figure, a pattern or a photograph on its printing surface. Since the printer apparatus is structured so that ink droplets from the printer head are accurately reached to the printing surface of the printing medium to perform a highly precise drawing, it is important that a space between the under face of the printer head (nozzle opening face) and the printing surface of the printing medium is appropriately adjusted to a predetermined gap. Therefore, the printing surface of the printing medium is normally required to be held by a medium support part so as to be located in a horizontal plane which is parallel to the under face of the printer head. However, when curling is occurred in the printing medium, the printing medium may be largely floated from the medium support part. In this state, when the printer head is moved on the printing medium for performing a predetermined printing, jamming may occur such that the printer head may collide with the floating portion of the printing medium and climb on the printing medium. In addition, when movement of the printer head is continued without recognizing the occurrence of the jamming, the printer head may be damaged due to friction against the printing medium.
As a technique which is capable of coping with this problem, a technique has been disclosed in which a contact type detection mechanism for detecting floating of a printing medium is disposed on both right and left sides in the moving direction of a carriage for scanning the printer head and, when the printing medium is provided with a floating portion exceeding the height of the under face of the printer head, the detection mechanism which is moved to right and left sides together with the carriage contacts with the floating portion to detect occurrence of jamming and stops movement of the carriage for preventing damage of the printer head (see, for example, Japanese Patent Laid-Open No. 2001-328246).
The detection mechanism in the conventional printer apparatus as described above detects occurrence of jamming by means of that a contact piece of the detection mechanism actually contacts with the floating portion of the printing medium. Therefore, when the detecting operation is repeatedly performed, the position of a drive part of the detection mechanism may be displaced by vibration or the contact piece is abraded by friction due to contacting with the printing medium to lower the detection accuracy. As a result, when the printer head and the printing medium are collided with each other, damage of the printer head may be occurred.